Vehicles such as trucks, buses, and construction machines use compressed air delivered by a compressor to control systems such as brakes and suspensions. Compressed air delivered by a compressor entrains water, which is contained in the atmosphere, and oil for lubricating the inside of the compressor. When the compressed air entraining such water and oil enters the systems, it causes rust and swelling of rubber members, resulting in an operational defect of the systems. For this reason, an air dryer is provided downstream of the above-mentioned compressor to remove water and oil from the compressed air.
An air dryer executes a loading mode operation for removing water and oil from compressed air by allowing the compressed air to pass through a desiccant and an unloading mode operation for regenerating the desiccant by ejecting water and oil trapped by the desiccant to the outside. The air ejected from the air dryer during the unloading mode operation entrains water and oil. Thus, considering the burden on the environment, it has been proposed to provide an oil separator for separating and recovering oil from the air ejected from the air dryer.
The oil separator separates gas and liquid by allowing air entraining water and oil to strike impingement members. Such gas/liquid separation causes the air from which water and oil have been removed to be expelled to the outside and the water and oil that have been separated from the air, which is collected liquid, to be recovered in a liquid storage portion in the oil separator (for example, see Patent Document 1).